50 lines
1.4 KiB
Rust
50 lines
1.4 KiB
Rust
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use common::*;
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#[derive(PartialEq, Debug)]
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pub enum Expression<'a> {
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Variable{name: &'a str, token: Token<'a>},
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String{cooked_string: CookedString<'a>},
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Backtick{raw: &'a str, token: Token<'a>},
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Concatination{lhs: Box<Expression<'a>>, rhs: Box<Expression<'a>>},
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}
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impl<'a> Expression<'a> {
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pub fn variables(&'a self) -> Variables<'a> {
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Variables {
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stack: vec![self],
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}
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}
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}
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impl<'a> Display for Expression<'a> {
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fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
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match *self {
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Expression::Backtick {raw, .. } => write!(f, "`{}`", raw)?,
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Expression::Concatination{ref lhs, ref rhs } => write!(f, "{} + {}", lhs, rhs)?,
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Expression::String {ref cooked_string} => write!(f, "\"{}\"", cooked_string.raw)?,
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Expression::Variable {name, .. } => write!(f, "{}", name)?,
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}
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Ok(())
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}
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}
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pub struct Variables<'a> {
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stack: Vec<&'a Expression<'a>>,
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}
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impl<'a> Iterator for Variables<'a> {
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type Item = &'a Token<'a>;
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fn next(&mut self) -> Option<&'a Token<'a>> {
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match self.stack.pop() {
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None | Some(&Expression::String{..}) | Some(&Expression::Backtick{..}) => None,
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Some(&Expression::Variable{ref token,..}) => Some(token),
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Some(&Expression::Concatination{ref lhs, ref rhs}) => {
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self.stack.push(lhs);
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self.stack.push(rhs);
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self.next()
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}
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}
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}
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}
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